I can try that, and see if I find the error(if it is some kind of software hardware issue), I don't need to do that with Davinci, or with After Effects, or Nuke or Premiere so I do feel that makes Fusion a non-Professional software.

I bought it really wanting to switch from after to it.

but this is not acceptable in a pro environment.Thank you for the tips will try them

Disabling OpenCL doesn't fix it. Disabling simultaneous branching doesn't fix it (although that only caused problems with single file outputs (MOVs or AVIs) in the past, and this error also occurs with image sequences). Graphics drivers (Nvidia 1080 Ti) are a month old.

Renders either come out as black frames, or as repeated frames, or totally out of order. I haven't had a successful render out of the software yet. Tried TIF sequences, PNG sequences, MOV, everything fails.

I've also had the problem with 9.01 and downgraded, which fixed it. Disabling open cl in the merge node options helped as well as someone else mentioned earlier here in the forum. But I don't want to do that every time so I downgraded. It's obviously a more or less commen problem.